相关论文: The Long-Term H$\alpha$ Emission Line Variation in…
The Halpha line emission formation region in the circumstellar disc of alpha Eri is: a) extended with a steep outward matter density decline during low H$\alpha$ emission phases; b) less extended with rather constant density distribution…
Emission lines formed in decretion disks of Be stars often undergo long-term cyclic variations, especially in the violet-to-red (V/R) ratio of their primary components. From observations of the bright Be-shell star zeta Tau, the possibly…
In this paper we present results of the spectroscopic analysis of H$\alpha$ line profile of the Be star 60 Cygni. We present time evolution of the equivalent width of the H$\alpha$ line profiles during years 1992 - 2016 and $V/R$ variation…
We analyzed V-band photometry of the Be star {\omega} CMa, obtained during the last four decades, during which the star went through four complete cycles of disc formation and dissipation. The data were simulated by hydrodynamic models…
Aims. We attempt to determine if a dependency on spectral subtype or vsini exists for stars undergoing phase-changes between B and Be states, as well as for those stars exhibiting variability in H{\alpha} emission. Methods. We analyse the…
A remarkable correlation between the H-alpha emission line and the radio behaviour of LSI+61 303 (V615 Cas, GT 0236+610) over its 4 yr modulation is discovered. The radio outburst peak is shifted by a quarter of the 4 yr modulation period…
We apply the viscous decretion disc (VDD) model to interpret the infrared disc continuum emission of 80 Be stars observed in different epochs. In this way, we determined 169 specific disc structures, namely their density scale, $\rho_0$,…
We present the first results on the spectra of Be/X-ray binary RX J0440.9+4431 obtained with the 2m Ritchey-Cretein-Coude telescope with Cassegrain Multi Mode Spectrograph (CMMS) (with R = 14000) at Terskol observatory. The H-alpha line…
An increasing number of AGNs exhibit broad, double-peaked Balmer emission lines, which are thought to arise from the outer regions of the accretion disk which fuels the AGN. The line profiles are observed to vary on a characteristic…
We present spectroscopic observations of the Be/X-ray binary X Per obtained during the period 1999 - 2018. Using new and published data, we found that during "disc-rise" the expansion velocity of the circumstellar disc is 0.4 - 0.7 km/s.…
An increasing number of AGNs exhibit broad, double-peaked Balmer emission lines, which arise from the outer regions of the accretion disk which fuels the AGN. The line profiles vary on timescales of 5--10 years. Our group has monitored a…
We present numerical models of the circumstellar disks of Be stars, and we describe the resulting synthetic H-alpha emission lines and maps of the wavelength-integrated emission flux projected onto the sky. We demonstrate that there are…
We report that the H_alpha emission line of RS Oph was strongly variable during our 2004 observations on a time scale of 1 month. The line consisted of both a double peaked central narrow component (FWHM ~ 220 km/s) and a strongly variable…
We analyse the spectroscopic and photometric variability of the Oe star HD 60848 over the last twenty five years. The spectra reveal recurrent, but irregular cycles of increased circumstellar emission lines. These cycles are highly…
FU Orionis systems are young stars undergoing outbursts of disc accretion and where the optical spectrum contains lines associated with both the disc photosphere and a wind component. Previous observations of the prototype FU Orionis have…
Nonlinear time-dependent calculations are being carried out in order to study the evolution of vertically-integrated models of non-selfgravitating, transonic accretion discs around black holes. In this paper we present results from a new…
We simulated the long-term collisional depletion of debris disks around solar-type (G2V) stars with our code. The numerical results were supplemented by, and interpreted through, a new analytic model. A few general scaling rules for the…
We present synthetic optical light curves of the hierarchical HD98800 quadruple system over a decade-long period when the circumbinary disc encircling the system's B binary is expected to eclipse the light from the A binary. We produce and…
We have observed variations in the optical emission lines from the X-ray binary Circinus X-1. These variations may be attributed both to orbital variations and to long term secular changes in line strength. We have detected double-peaked…
We have obtained optical spectroscopy and photometry data during four years after the event. The long-term photometric light-curve and the equivalent widths of the Halpha and He I 6678 lines were used to monitor the state of the Be star…